In the exploration of oil, gas and geothermal energy, drilling operations are used to create boreholes, or wells, in the earth. Modern drilling rigs not only have drilling capability, but they also have pipe handling capability to allow simultaneous drilling and pipe handling operations
Conventional drilling involves having a drill bit on the bottom of the well. A bottom-hole assembly is located immediately above the drill bit where directional sensors and communications equipment, batteries, mud motors, and stabilizing equipment are provided to help guide the drill bit to the desired subterranean target. A set of drill collars are located above the bottom-hole assembly to provide a noncollapsible source of weight to help the drill bit crush the formation. Heavy weight drill pipe is located above the drill collars for safety. The remainder of the drill string is mostly drill pipe, designed to be under tension. Each drill pipe is roughly 30 feet long, but lengths vary based on the style. It is common to store lengths of drill pipe in “doubles” (two connected lengths) or “triples” (three connected lengths) or even “quadruples” (four connected lengths). A “tubular stand” refers to connected sections of drill pipe, drill collars, or casing.
When the drill bit wears out, or when service, repairs or adjustments need to be made to the bottom-hole assembly, the drill string (drill pipe and other components) is removed from the wellbore and setback. When removing the entire drill string from the well, it is typically disconnected and setback in doubles or triples until the drill bit is retrieved and exchanged. This process of pulling everything out of the hole and running it all back in the hole is known as “tripping.”
Tripping is non-drilling time and, therefore, an expense. Efforts have long been made to devise ways to avoid it or at least speed it up. Running triples is faster than running doubles because it reduces the number of threaded connections to be disconnected and then reconnected. Triples are longer and therefore more difficult to handle due to their length and weight and the natural waveforms that occur when moving them around. Manually handling moving pipe in the derrick and at the drill floor level can be dangerous.
It is desirable to have drilling rig processes for handling pipe in a more efficient and timely manner without sacrificing safety.
Most attempts to automate pipe handling are found offshore. However, solutions for pipe delivery on offshore drilling rigs are seldom transferable to onshore land rigs, due to the many differences in economic viability, size, weight, and transportation considerations.